The U.S. military's cybersecurity capabilities aren't advancing fast enough to stay ahead of the "onslaught of multipronged" attacks envisioned by adversaries, the Pentagon's combat testing office is warning.

Despite some progress in fending off attacks staged by in-house "Red Teams," the testing office said, "We estimate that the rate of these improvements is not outpacing the growing capabilities of potential adversaries who continue to find new vulnerabilities and techniques to counter fixes."

Automation and artificial intelligence are beginning to "make profound changes to the cyber domain," a threat that the military hasn't yet fully grasped how to counter, Robert Behler, the Defense Department's director of operational test and evaluation, said in his annual assessment of cyber threats, which was obtained by Bloomberg News.

The test office's findings may be discussed on Tuesday during a Senate Armed Services hearing focused on Pentagon cyber policy with Chief Information Officer Dana Deasy.

The evaluation, part of the testing office's annual report that may be released as early as this week, comes amid other critical appraisals of the military's ability to maintain and improves its defense against computer attacks.

In an acknowledgment of potential threat from artificial intelligence, the Army is seeking information about "Autonomous Cyber" capabilities that would use AI and machine learning to defend its networks and protect its own intelligent systems against sophisticated cyberattacks. In other words, the Army wants to pit AI against AI in cyberspace, according to Bloomberg Government analyst Chris Cornillie.

In October, the Government Accountability Office issued a withering assessment, saying the U.S. military had failed to make cybersecurity for its multibillion-dollar weapons systems a major focus until recently, despite years of warnings.

"We have not reviewed the latest report" from Behler "but DOD faces significant challenges in securing its weapon systems from cyber threats," Cristina Chaplain, the GAO director who managed the agency's report, said in an email.

She said "DOD testers routinely found mission-critical vulnerabilities in systems under development, and in some cases, repeatedly over the years," and program officials "tended to discount the scale and severity of the problem."

Behler's report reinforces those concerns, saying the Pentagon's cyber testing is "handicapped by lack of expertise" and tools to assess software-intensive weapons systems.

Among the test results cited in assessment:

The Air Force found "suggested areas for needed cybersecurity hardening" when it conducted tests last year of initial capabilities for Raytheon Co.'s ground-control network for new GPS III satellites.

Cybersecurity testing of Lockheed Martin Corp.'s F-35, a flying computer with eight million lines of code, "showed that some of the vulnerabilities identified during earlier testing periods still had not been remedied."

Red Teams recently conducted three successful cyber attacks on the new Defense Department-Department of Veterans Affairs health care records management system known as Genesis that showed it "is not survivable in a cyber-contested environment."

Analyzing four years of after-action reports on cyber exercises, Behler's office report found "defenders demonstrated increasing ability to detect Red Team activity." But it also said "defenders need to improve speed and accuracy for processing reported incidents."

Red Teams operated by the Army's Threat Systems Management Office conducted more than 200 penetration events in fiscal 2018. While the mock attackers succeeded in many cases, there were "a growing number of instances where Red Teams needed more time" to achieve their objectives partly thanks to "improved network defenses," the testing office said.

Behler also warned of a crisis in recruiting and retaining qualified Red Team commandos, who attempt damaging penetrations of networks and weapons systems using the tactics of adversaries such as Russia, China, North Korea or Iran.

Most Pentagon cybersecurity jobs "are not compensated commensurate with the position's required time and expertise," increasing the risk of losing trained personnel to higher-paying private work, according to the report.

Behler suggested the Pentagon should provide seed funding for a select group of military service academies, private companies, universities and national laboratories "to grow the DoD's cybersecurity testing workforce and capabilities" while developing automated tools because "hiring more cyber experts will not be enough."